In the past, dehydrated larvae of the Polypedilum vanderplanki had been prepared in the following manner. Specifically, a piece of filter paper and 440 μl of distilled water were put in a dehydration vessel (a glass petri dish with a diameter of 6 cm) with approximately 10 larvae, the dehydration vessel was set in a desiccator with humidity of 5% or lower, and the content of the desiccator was subjected to dehydration for a period of two days. However, dehydrated larvae often stuck to filter paper or a glass surface, and their bodies were often damaged when they were collected from the dish. Such larvae died from blood loss when they were rehydrated. Since this procedure required careful handling of insect larvae one by one, an extremely long period of time was needed in order to recover a large quantity of larvae.
When a large number of dehydrated larvae were transferred to another vessel, those larvae would not stick to the wall or the like in the vessel. Accordingly, the dehydrated larvae they faced possible physical damage due to oscillation caused upon transportation of the larvae-containing vessel.
The applicant of the present application has filed for a patent “a method for dehydrating and preserving tissues of multicellular organisms at ordinary temperature” (JP Patent Application No. 2003-72585). This invention has been completed with the discovery of conditions for inducing drought dormancy and conditions for dehydration, wherein tissues of multicellular organisms, particularly those of Polypedilum vanderplanki, are gradually dehydrated while culturing to achieve a state of complete dehydration and then rehydrated to recover from cryptobiosis.
With this technique, however, cryptobiotic larvae could not be effectively produced within a short period of time.
Polypedilum vanderplanki inhabits Africa exclusively and lives exclusively in small puddles in rocky areas. Since they are very susceptible to natural enemies or interspecies competition, they cannot propagate themselves in large puddles or ponds that are wet all year round (McLachlan, A., 1983, Life-history tactics of rain-pool dwellers, Journal of Animal Ecology 52: 545-561). When adult insects escape from a laboratory in Japan, however, the possibility that they would propagate themselves cannot be completely denied. In such a case, they could significantly affect the indigenous ecosystem.
Use of larvae of Polypedilum vanderplanki as educational materials has been attempted. In order to realize such attempt, it is required to supply sufficiently dehydrated larvae so that they can be easily utilized as educational materials or the like. At the same time, the risk of ecosystem disruption must be avoided in case such larvae escape. Thus, there remain many problems to be resolved, as mentioned above.